Scholomance Academy Cards List & Guide
Set the enemy hero's remaining Health to 1.
Kabal Lackey + Counterspell.
This actually worked- it took me about 30 restarts to get both cards in my opening hand, but it did successfully counter the spell.
There are no cards that produce this. The only place this is used is in the Arthas Boss in the Frozen Throne Adventure.
He uses 9 different spells depending on what class you fight him with. This one happens to be when you are playing a Mage.